Bioshock doesn't feel like a game, which is perhaps the finest praise a video game can receive. An "experience" is a more fitting description, for it succeeds at fully immersing you within the world it creates. This is an adventure that deserves to be taken, and one you won't soon forget.
A plane crashes into the middle of the ocean, and one lone survivor discovers a mysterious lighthouse - a structure which serves as entrance to the underwater city of Rapture. Intended as an underwater utopia, where citizens could live without the oppressiveness of government, religion, and politics (the cause of all unrest), Rapture was a city of hope, where merit was earned and unjustly taken from no one, a haven for science, with the desire to improve the human species. This ideology, flawless though it may seem, failed to take into account humanities many faults, and Rapture crumbled into a city of violence, carnage, and desperation.
This is where Bioshock begins.